Ensemble forecasting study on an extensive snowfall in the western U.S. using RSM

EOS project of NASA supports ensemble forecasting of precipitation over the Colorado River Basin. In February of 2002, the Regional Spectral Model (RSM) developed in the National Centers of Environmental Prediction (NCEP) has been installed in the University of Arizona. This study shows an example for West USA with extensive precipitation. The ensemble forecasting system of RSM (hydrostatic version) and MSM (non-hydrostatic version) was used to make 48 and 72-hour precipitation forecasts in the western U.S., in which an extensive snowfall event was successfully predicted. The ensemble forecasting results are evaluated in comparison with ground observation data combining radar verification. In addition, the influence of using high resolution modeling and different forecasting period on the ensemble forecasts is also addressed. Brier skill analysis indicates that the predictability of ensemble forecasting is varied by region, scale, and time.